Fuel hose

Abstract

A fuel hose which has excellent permeation resistance to gasoline, sour gasoline resistance, amine resistance and low temperature properties, and has excellent electrical conductivity. The fuel hose has a laminate structure comprising an innermost layer made of the rubber blend (A) of an acrylic rubber and an acrylonitrile-butadiene rubber wherein acrylonitrile is present in a proportion of 15 wt % to 30 wt %, or an acrylic rubber (B) having a skeleton derived from acrylonitrile in its molecular skeleton, and a fluororesin layer formed on a peripheral surface of the innermost layer.

Description

BACKGROUND OF THE INVENTION [0001] 1. Field of the Invention [0002] The present invention relates to a fuel hose for transporting fuels such as gasoline, alcohol-containing gasoline (gasohol), alcohol, hydrogen, light oil, dimethyl ether, liquefied petroleum gas (LPG), compressed natural gas (CNG) or the like. [0003] 2. Description of the Art [0004] With growing worldwide awareness of environmental issues, the control of the amount of hydrocarbon vapor emission from an automotive fuel hose has been enhanced. Particularly in the United States, stringent regulations against vapor emission have come into effect. To cope with the hydrocarbon vapor emission control in this situation, multi-layer hoses have been proposed which include a rubber layer, a resin layer, a reinforcing layer and the like. Such a multi-layer hose generally uses a polyamide resin, acrylonitrile-butadiene rubber (NBR), a nitrile-polyvinyl chloride rubber (NBR -PVC), a fluororesin and the like as a material for the ...

AI Technical Summary

Benefits of technology

[0015] Further, the inventors found that when an innermost layer of a hose was made of an acrylic rubber (B) having a skeleton derived from acrylonitrile in its molecular skeleton so as to incorporate a specific amount of acrylonitrile into the molecular skeleton of the acrylic rubber, polarity is increased so as to become generally in compatible with an fuel oil having a low polarity, resulting in an improved resistance to a fuel oil while retaining good low temperature properties, good electrical conductivity and the like, and further adhesion with a fluororesin, excellent in permeation resistance to gasoline, was also confirmed to such a degree as no adhesive is required for bonding therebetween according to the situation.

Problems solved by technology

However, a polyamide resin is insufficient in resistance to sour gasoline which is the result of oxidation of gasoline (sour gasoline resistance being particularly important in applications to fuels).

Similarly, NBR is also insufficient in sour gasoline resistance.

NBR•PVC contains PVC, which may deteriorate the environment, and has poor low temperature properties, and further is not conformable to the above-mentioned regulations against vapor emission.

For example, a hose having the innermost layer made of a fluororesin has a poor sealing property and also is difficult to join with other parts due to its rigidity, which may result in leakage of fuel and the like.

However, if such a hose as proposed in the above-mentioned Publication adopts an innermost layer of NBR, the resulting hose is drastically deteriorated in sour gasoline resistance, as mentioned above.

Alternately, if such a hose as proposed in the same Publication adopts an innermost layer of FKM, an adhesive property between the FKM and a fluororesin layer is bad, which requires interlaminar bonding by means of an adhesive, resulting in complicated production and an possible increase in its production cost.

Further, since the latter hose has an inferior low-temperature property (a sealing property when in use at an extremely low temperature (about −30° C.

However, in a hose having the innermost layer made of FKM, since FKM itself has substantially high electrical resistance, it is difficult to impart sufficient electrical conductivity, even with the addition of an electrically conductive agent such as carbon black.

Alternately, if an amount of an electrically conductive agent blended is increased so as to impart sufficient electrical conductivity, the mechanical strength of the innermost layer is decreased, which may result in a deterioration in the sealing property.

Images